So, I know that some people like the idea of a tiny house so that they can move out to their little plot of land in the country, living in the TH until such time as they can build their cob or strawbale home. The main drawback I see with that plan is the commute-- if you're still working the "day job".
As an alternative, my wife and I are exploring the "shared house" concept that Paul talks of in his "Permaculture Bricks" keynote speech video. Instead of cramming all your living into <250 sq. feet, we feel there's a place for sharing a 2400 sq.ft. home with 2 or 3 other couples (and maybe a few little-ones).
We can actually afford the mortgage on our own, and we might start out by registering on airBNB as we look for permanent housemates, but the idea is to "stack functions" by sharing this as communal space.
Communal living also allows for savings of time and money in other ways that a tiny house on its own can't match.
Our goal is to stay near the city, so we can keep our "day jobs" for a while. The money saved in communal living will allow us to pay down our student loans and other debts, and then build the financial resources for a better piece of land further out from town. Perhaps some of our housemates will go in with us on the project, too.
You have to figure out what is more important to you.
However having a tiny house means that
You save on rent/mortgage but the bad = more money spend in gas and time on the road.
You get to plant and observe your food forest now vs 4 years later.
You get to be mentally prepare for a homesteading lifestyle.
You get to slowly build your water/well system
You get to slowly build your sewer system
You get to slowly build your house yourself over a 3+ year timespan monthly as money is saved.
You are already living the life vs possible getting comfortable and fat in the 'city'
If the economy turns south (companies go bankrupt or bought out all the time), you are already there still building vs spending all you saving.
If you are already onsite more of your friends family will come over and they can help out.
All that said, if you can't convince your wife of the pros listen to her and stay in the city.